PRR D2

Infobox Locomotive
name = PRR D2 & D2a
powertype = Steam

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caption = Class B A #138 (later class D2a)
builder = PRR Altoona Works
builddate = 1868–1872 (D2); 1881–1882 (D2a)
totalproduction = 20 (D2); 45 (D2a)
whytetype = 4-4-0
uicclass = 2'C
gauge = RailGauge|ussg
leadingsize = convert|28|in|abbr=on (D2)
convert|30|in|abbr=on (D2a)cite web |title = Class D2 diagram |url = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=d2a_oldba.gif&sel=ste&sz=sm&fr= |author = Pennsylvania Railroad |publisher = PRR.Railfan.net |accessdate = 2008-08-19]
driversize = convert|62|in|abbr=on
convert|68|in|abbr=on (D2a)
wheelbase = convert|22|ft|5.625|in|abbr=on (D2 & D2a)
length = convert|54|ft|5.44|in|abbr=oncite web |title = Class D2a diagram |url = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=d2.gif&sel=ste&sz=sm&fr= |author = Pennsylvania Railroad |publisher = PRR.Railfan.net |accessdate = 2008-08-19]
width = convert|9|ft|0.94|in|abbr=on
height = convert|14|ft|8|in|abbr=on (D2)
convert|14|ft|11|in|abbr=on (D2a)
weightondrivers = convert|52500|lb|abbr=on (D2)
convert|53750|lb|abbr=on (D2a)
weight = convert|80500|lb|abbr=on (D2)
convert|82200|lb|abbr=on (D2a)
tenderweight = convert|51400|lb|abbr=on (D2 & D2a)
locotenderweight = convert|131900|lb|abbr=on (D2)
convert|133600|lb|abbr=on
tendertype = Eight-wheel with water scoop
fueltype = Soft coal
fuelc
convert|8000|lb|abbr=on
waterc
convert|2400|usgal|abbr=on The Pennsylvania Railroad's steam locomotive class D2 (formerly Class B, pre-1895) comprised twenty 4-4-0 locomotives intended for mountain passenger helper service, constructed at the railroad's own Altoona Works during 1869–1880. cite web
title = PRR Steam Roster
url = http://www.northeast.railfan.net/prr_steam2.html
work = Northeast Rails
accessdate = 2007-12-31] They were the second standardized class of locomotives on the railroad and shared many parts with other standard classes.cite book
title = The Pennsylvania Railroad
first = James
last = Dredge
year = 1879
publisher = "Engineering" magazine
location = London]

This design differed from the Class A (later D1) mainly in its smaller drivers for greater tractive effort in mountainous terrain. Like all the early standardized 4-4-0s on the PRR, the Class B had a wagon-top boiler with steam dome and a firebox between the two driving axles.

In 1881, the PRR took the Class B design and modified it to produce more locomotives for express passenger service, with convert|68|in|adj=on drivers like the earlier Class A. These new locomotives were designated Class B A, and were classified as B2a in the post-1895 scheme; forty-five of them were constructed.cite book
title = Motive Power Development on the Pennsylvania Railroad System
first = Paul T.
last = Warner
year = 1924
publisher = Baldwin Locomotive Works
location = Philadelphia]

References